Amidst daily aggravating environmental pollution, the impact of household sewage on contamination of water resources has now become a serious social problem. The environmental pollution caused by various types of synthetic detergents in use in the laundering of clothes has been analyzed to find:
1) that they increase BOD (biological oxygen demand) of the water of rivers and streams because of their low biodegradability;
2) that they give rise to lots of foam on the surface of rivers and streams through their propensity to cause air foam even at low concentration, whereupon the foam hinders oxygen in the atmosphere from dissolving into the water by blocking the passage of the sun's rays, resulting in a decrease of the amount of the oxygen dissolved in the water, and leads to the decay of the water;
3) and that they cause destruction of nature by doing harm to ecological system (aquatic life) due to their strong toxicity.
Now, the problem of water contamination is aggravated by the increase in household sewage due to the increase in population, and in order to solve this problem it is desirable to use natural detergents like soap that has high biodegradability, low effervescence, and low toxicity. However, natural detergents, inferior to synthetic detergents in their cleaning capability and inconvenience in use, can hardly satisfy housewives used to synthetic detergents. Hence a demand for production of a low pollution powder detergent having high detergency and convenience in use.
The present inventors have continued their study with the view of the development of a low pollution powder detergent which can reduce water contamination and provide a detergency and convenience equal to or better than the existing synthetic detergents. As a result, the inventors have discovered that a composition of fatty acid ester, soap, soda ash, and fatty acid amide in a certain ratio, plus certain inorganic materials added thereto, can achieve the objectives given above. On the basis of this discovery, the present invention has been completed.